While we took a little time off for the holidays (and moved web hosts), we didn’t want to miss commenting on Inside Windows Live, the new Windows Live engineering blog over at the Windows Blog. We decided to hold our tongue after a welcome post and the obligatory “we’re not going to talk about the future” post got the blog off to a bit of a slow start, and we’re glad we did. Even though we missed commenting on this latest post from just before Christmas, we think it’s too good to miss.

In “A peek behind the scenes at Hotmail”, Arthur de Haan makes up for the first two posts with some very interesting numbers about the massive scale of a project that is Hotmail. de Haan lays out some of the facts:

We are a worldwide service, delivering localized versions of Hotmail to 59 regional markets, in 36 languages.

We host well over 1.3 billion inboxes (some users have multiple inboxes)

Over 350 million people are actively using Hotmail on a monthly basis (source: comScore, August 2009).

We handle over 3 billion messages a day and filter out over 1 billion spam messages – mail that you never see in your inbox.

We are growing storage at over 2 petabytes a month (a petabyte is ~1 million gigabytes or ~1000 terabytes).

We currently have over 155 petabytes of storage deployed (70% of storage is taken up with attachments, typically photos).

We’re the largest SQL Server 2008 deployment in the world (we monitor and manage many thousands of SQL servers).

Microsoft needs to talk more about the services they have to offer, in our opinion, and we think it’s great that the new blog is beginning to do just that. Congratulations again to the Windows Live team for getting this off the ground, keep up the good work and can’t wait for more!